Transfer machines are known in practice in many variations. They are linked together, for example, by cyclically operating conveying means, such as in the form of rails or transfer bars. In the machines, the machining units are disposed transverse to the feed device. Before a workpiece can perform the next cycle and be replaced by an unmachined piece, the corresponding machining unit must be moved to an idle position. It can only resume its working position when the unmachined workpiece has been positioned and clamped in place. Because of this operating scheme, this mode of operation results in significant nonproductive periods. To reduce the nonproductive time, DE 37 22 180 provides clamping devices opposite one another on both sides of the conveying device. While one clamping device is being loaded and unloaded, the workpiece clamped in the other clamping device is being machined. From DE 41 42 121 A1 (U.S. Pat. No. 5,361,485), we know of a transfer machine for machining differential housings. In the machining stations, work rests comprising clamping and locating mechanisms are provided for the workpieces, the contact areas at which the locating surfaces come in contact with the workpieces being the same in every machining station. This transfer machine is configured specifically for machining differential housings.